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2006 Philadelphia Annual Meeting (22–25 October 2006)

Paper No. 11
Presentation Time: 10:45 AM

NEAR-FIELD STRATIGRAPHIC RECORD OF THE LATE PALEOZOIC GONDWANAN ICE AGE FROM EASTERN AUSTRALIA DISCLOSES MULTIPLE, ALTERNATING GLACIAL AND NON-GLACIAL INTERVALS


FIELDING, Christopher R., Department of Earth & Atmospheric Sciences, University of Nebraska - Lincoln, 214 Bessey Hall, P.O. Box 880340, Lincoln, NE 68588-0340, RYGEL, Michael C., Department of Geology, State University of New York at Potsdam, 44 Pierrepont Ave, Potsdam, NY 13676, FRANK, Tracy D., Department of Geosciences, Univ of Nebraska-Lincoln, 214 Bessey Hall, Lincoln, NE 68588-0340, BIRGENHEIER, Lauren P., Department of Geosciences, University of Nebraska - Lincoln, 214 Bessey Hall, P.O. Box 880340, Lincoln, NE 68588-0340, JONES, Andrew T., Geoscience Australia, GPO Box 378, Canberra, 2601, Australia and ROBERTS, John, School of Biological, Earth, and Environmental Sciences, University of New South Wales, Sydney, 2052, Australia, cfielding2@unl.edu

We have carried out a comprehensive re-evaluation of stratigraphic records of the late Paleozoic Gondwanan Ice Age (LPGIA) in Queensland and New South Wales, eastern Australia. In contrast to most previous studies, our investigation has shown that the time distribution of facies indicative of glaciation in eastern Australia is sporadic. We here reinterpret the LPGIA in eastern Australia as a series of discrete (2-8 m.y.) glacial intervals separated by non-glacial periods of comparable duration. Four glacial intervals are recognized within the Upper Carboniferous (uppermost Mississippian to Pennsylvanian; C1: c. 328-326 Ma, C2: c. 322.5-319.5 Ma, C3: c. 317.5-315 Ma, C4: c. 313-307.5) and four within the Permian (P1: c. 299-291 Ma, P2: c. 287-280 Ma, P3: c. 273-268 Ma, P4: c. 267-261 Ma). Internal glacial/interglacial cyclicity can be recognized within some of these intervals. Up until shortly before glacial C1, benign climatic conditions allowed the widespread formation of oolitic limestones across eastern Australia, suggesting an abrupt transition into the LPGIA. Strata within each glacial interval indicate the presence of ice caps proximal to the various sedimentary basins. Strata within intervening non-glacial intervals preserve evidence of mainly fluvial and lacustrine environments in the Carboniferous and fluvial to shallow marine environments in the Permian with no evidence of glacial influence. The temporal distribution and duration of glacial periods indicates progressively more long-lived glacial conditions through several glacial intervals from mid-Carboniferous into Early Permian times, followed by progressive amelioration into the Late Permian. This distribution may help to explain patterns of Gondwanan ice extent inferred by other workers, and is consistent with interpretations of paleo-equatorial climatic cyclicity derived from paleobotanical and geochemical proxy datasets.

Session No. 127

T9. “Ice House” / “Hothouse” – An Analysis of Late Paleozoic Floras and Their Response to Global Climate Change
Tuesday, 24 October 2006: 8:00 AM-12:00 PM
Geological Society of America Abstracts with Programs. Vol. 38, No. 7, p.317
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